1. Field of the Invention
The present invention relates to control systems for gas turbines, and in particular to a control system having both a fuel controller and a combustion air controller.
2. Description of Prior Art
Gas turbines are commonly coupled to electric generators to drive the generator. It is known to control the amount of fuel and air supplied to a combustion chamber of the gas turbine using a cross channel controller. Known cross channel controllers operate on a turbine speed error signal that is an input to a fuel supply controller. Such cross channel controllers process the speed error signal, and the resulting processed speed error signal is added to a turbine exhaust temperature error signal. The sum of the turbine exhaust temperature error signal and processed speed error signal is processed by an air supply controller using a transfer function, to generate a control signal that controls air supplied to the combustion chamber. See, for example, U.S. Pat. No. 5,487,265 (Jan. 30, 1996) and U.S. Pat. No. 5,636,507 (Jun. 10, 1997).